The Interaction of Cumulene Systems with Organometallic π-Complexes. IV. Novel π-Allyl Complexes Obtained from the Reactions of Allene with Iron and Cobalt Carbonyls

Abstract 2,2′-Bi-π-allylene(hexacarbonyl)di-iron, [(OC)3Fe]·(Remark: Graphics omitted.)·[Fe(CO)3], was found to be a product of the reaction of allene with Fe3(CO)12. A study of the NMR spectrum, however, showed that a rapid valence tautomerisation takes place, even at −10°C between the 2,2′-bi-π-allylene structure and the related butadiene-type structure. In the presence of an excess of Co2(CO)8, allene yielded the [(C3H4)Co(CO)3]2 complex. The structure of this complex in which a (Remark: Graphics omitted.) skeleton was bound to two Co(CO)2 groups via π-allyl and acyl groups, was suggested.